目的：研究不同周龄脂蛋白脂酶(LPL)基因敲除小鼠糖脂代谢情况,并探究其胰岛素抵抗的可能机制。方法分别选取16周和40周 LPL 基因敲除杂合子小鼠(LPL+/-)和野生型(WT)C57小鼠作为实验对象,将其分为4组：16周 LPL+/-组(n=6)、16周 WT 组(n=6)、40周 LPL+/-组(n =6)和40周WT 组(n=6)。注射肝素后,分别测定 LPL+/-小鼠及 WT 小鼠血清 LPL 活性；检测4组小鼠血清甘油三酯和游离脂肪酸水平；行腹腔葡萄糖耐量试验(IPGTT)监测血糖变化,计算葡萄糖曲线下面积(AUCG)和稳态模型评估的胰岛素抵抗指数(HOMA-IR)、稳态模型评估的β细胞功能指数(HOMA-β),评价胰岛素敏感性及胰岛β细胞功能；采用比色法测定血清丙二醛和总抗氧化力水平；用二氢乙啶(DHE)荧光染色法检测肝脏和骨骼肌中活性氧簇(ROS)水平。结果16 和40周龄 LPL+/-组小鼠 LPL 活性均明显低于同周龄WT 组小鼠(P<0.05)。40周龄 LPL+/-组小鼠血清甘油三酯和游离脂肪酸水平显著高于同周龄 WT 组小鼠(P<0.05),也明显高于16周龄 LPL+/-组小鼠甘油三酯、游离脂肪酸水平(P<0.05)。与同周龄 WT 组比较,40周龄 LPL+/-组小鼠 IPGTT 30、120 min 血糖明显上升(P<0.05),空腹胰岛素、HOMA-IR 显著升高(P<0.05)。40周龄 LPL+/-组小鼠血清丙二醛明显升高(P<0.05),总抗氧化力显著降低(P<0.05)。16周龄 LPL+/-组小鼠骨骼肌中 ROS 表达水平显著增加,而40周龄 LPL+/-小鼠中肝脏、骨骼肌 ROS 水平均明显高于同周龄 WT 组小鼠。结论 LPL+/-小鼠随着年龄增长,脂代谢紊乱加重,血糖升高且出现明显胰岛素抵抗。血脂异常的 LPL+/-小鼠产生的胰岛素抵抗可能与氧化应激有关。%Objective To investigate the glucolipid metabolism in lipoprotein lipase (LPL) gene knockout mice, and to explore the possible mechanisms of insulin resistance. Methods 16- and 40-week old LPL gene knockout heterozygous mice( LPL + / -) and wild type ( WT) C57 mice were selected and divided into 4 groups:16-week LPL+ / -(n=6), 16-week WT(n = 6), 40-week LPL+ / -(n = 6), and 40-week WT(n = 6) group. LPL activity of post-heparin serum was examined. Serum triglyceride( TG) and free fatty acid( FFA) were measuzed. Intraperitoneal glucose tolerance test(IPGTT) in 4 groups of mice were performed. The glucose area under the curve (AUCG) and homeostasis model assessment for insulin resistance index and β-cell function index ( HOMA-IR, HOMA-β) were calculated to evaluate insulin sensitivity and the function of islet β-cells. Serum malondialdehyde (MDA) and total antioxidant capacity ( TAOC) levels were determined by means of colorimetric method. Using dihydroethidium( DHE) fluorescent staining method, reactive oxygen species ( ROS) levels in liver and skeletal muscle were determined. Results LPL activity levels of both 16- and 40-week LPL+ / - mice were significantly lower than that in WT mice of the same age. Serum TG and FFA of 40-week old LPL+ / - mice were significantly higher than those in WT mice of the same age(P<0. 05), and they were also higher than those of 16-week old LPL+ / - mice(P<0. 05). IPGTT showed that compared with WT mice, blood glucose level in LPL+ / - mice was significantly higher than that in WT group at 30 and 120 minute(P<0. 05), and fasting insulin and HOMA-IR were increased significantly(P<0. 05). Serum MDA of 40-week old LPL+ / - mice was evidently higher than that in WT mice by the same week(P<0. 05), while TAOC level was lower than that of WT mice (P<0. 05). ROS in skeletal muscle of 16-week old LPL+ /- mice was significantly increased. Meanwhile, ROS in both liver and skeletal muscle of 40-week old LPL+ / - mice was significantly higher than that in WT mice of the same age. Conclusion As time goes by, lipid and glucose disorders of LPL+ / - mice are aggravating, and insulin resistance develops evidently. Insulin resistance in LPL+ / -mice with dyslipidemia may be related to oxidative stress.
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